Exhaust system for motorcycle

An exhaust system for a motorcycle, comprising:

• an exhaust pipe connected to an engine;
• and
• a silencer connected to the exhaust pipe, the silencer comprising:
• a hermetically sealed first tubular body;
• and
• a second tubular body coaxially disposed within the first tubular body, the second tubular body having a front end portion connected to the exhaust pipe and a rear end portion opened toward the atmosphere, wherein the second tubular body includes a reduced diameter portion with a diameter which becomes smaller in the downstream direction, a throttle portion connected to the downstream end of the reduced diameter portion and having a constant diameter, and an enlarged diameter portion connected to the downstream end of the throttle portion, the enlarged diameter portion having a diameter which becomes larger in the downstream direction, wherein the diameter of the upstream end of the enlarged diameter portion is equal to the constant diameter of the throttle portion, wherein the throttle portion is bent such that the longitudinal axis of the enlarged diameter portion is directed at a lower slope than a longitudinal slope of a main tube portion of the second tubular body in a state where the exhaust system is mounted on the motorcycle.

An exhaust system for a motorcycle, comprising:

• an exhaust pipe connected to an engine;
• and
• a silencer connected to the exhaust pipe, the silencer comprising:
• a hermetically sealed first tubular body;
• and
• a second tubular body coaxially disposed within the first tubular body, the second tubular body having a front end portion connected to the exhaust pipe and a rear end portion opened toward the atmosphere, wherein the second tubular body includes a reduced diameter portion with a diameter which becomes smaller in the downstream direction, a throttle portion connected to the downstream end of the reduced diameter portion and having a constant diameter, and an enlarged diameter portion connected to the downstream end of the throttle portion, the enlarged diameter portion having a diameter which becomes larger in the downstream direction, wherein the diameter of the upstream end of the enlarged diameter portion is equal to the constant diameter of the throttle portion, wherein the silencer further comprises an absorbing mechanism which permits the first tubular body and the second tubular body to slide relative to one another to absorb the difference between thermal expansion amounts of the first and second tubular bodies caused by a temperature difference between the first tubular body and the second tubular body, and wherein the throttle portion includes a straight tube portion connected to the reduced diameter portion and a bent tube portion connected to the enlarged diameter portion such that the bent tube portion is disposed opposite to the straight tube portion with a gap therebetween.

An exhaust system for a motorcycle, comprising:

• an exhaust pipe connected to an engine;
• and
• a silencer connected to the exhaust pipe, the silencer comprising:
• a hermetically sealed first tubular body;
• and
• a second tubular body coaxially disposed within the first tubular body, the second tubular body having a front end portion connected to the exhaust pipe and a rear end portion opened toward the atmosphere, wherein the second tubular body includes a reduced diameter portion with a diameter which becomes smaller in the downstream direction, a throttle portion connected to the downstream end of the reduced diameter portion and having a constant diameter, and an enlarged diameter portion connected to the downstream end of the throttle portion, the enlarged diameter portion having a diameter which becomes larger in the downstream direction, wherein the diameter of the upstream end of the enlarged diameter portion is equal to the constant diameter of the throttle portion, wherein the throttle portion includes a straight tube portion and a bent tube portion, and wherein a gap is provided between the straight tube portion and the bent tube portion.

An exhaust system for a motorcycle, comprising:

• an exhaust pipe connected to an engine;
• and
• a silencer connected to the exhaust pipe, the silencer comprising:
• a hermetically sealed first tubular body;
• and
• a second tubular body coaxially disposed within the first tubular body, the second tubular body having a front end portion connected to the exhaust pipe and a rear end portion opened toward the atmosphere, wherein the second tubular body includes a reduced diameter portion with a diameter which becomes smaller in the downstream direction, a throttle portion connected to the downstream end of the reduced diameter portion and having a constant diameter, and an enlarged diameter portion connected to the downstream end of the throttle portion, the enlarged diameter portion having a diameter which becomes larger in the downstream direction, wherein the throttle portion includes a straight tube portion connected to the reduced diameter portion and a bent tube portion connected to the enlarged diameter portion such that the bent tube portion is disposed opposite to the straight tube portion with a gap therebetween, wherein the gap is formed around an axis of the second tubular body so that the downstream end of the straight tube portion and the upstream end of the bent tube portion face each other on opposing sides of the gap.